Simultaneous Removal of Polymers with Different Ionic Character from Their Mixed Solutions Using Herb-Based Biochars and Activated Carbons

Abstract

Nettle and the sage herbs were used to obtain carbonaceous adsorbents. For the biochar preparation the precursors were dried and subjected to conventional pyrolysis. Activated carbons were obtained during precursor impregnation with phosphoric(V) acid and multistep pyrolysis. The textural parameters and acidic-basic properties of the obtained adsorbents were studied. The activated carbons prepared from the above herbs were characterized by the largely developed specific surface area. The obtained carbonaceous adsorbents were used for polymer removal from aqueous solution. Poly(acrylic acid) (PAA) and polyethylenimine (PEI) were chosen, due to their frequent presence in wastewater resulting from their extensive usage in many industrial fields. The influence of polymers on the electrokinetic properties of activated carbon were considered. PAA adsorption caused a decrease in the zeta potential and the surface charge density, whereas PEI increased these values. The activated carbons and biochars were used as polymer adsorbents from their single and binary solutions. Both polymers showed the greatest adsorption at pH 3. Poly (acrylic acid) had no significant effect on the polyethylenimine adsorbed amount, whereas PEI presence decreased the amount of PAA adsorption. Both polymers could be successfully desorbed from the activated carbons and biochar surfaces. The presented studies are innovatory and greatly required for the development of new environment protection procedures.

Investigation of Ionic Polymers’ Stabilizing and Flocculating Properties in Dispersed Activated Carbons Systems

“…The plant material was impregnated in a H 3 PO 4 solution for 24 h and then subjected to a two-stage heating program (200 • C and 500 • C) for adsorbent preparation. The detailed procedure for adsorbents preparation was described in our previous paper [17]. The textural characterization of the activated carbons was based on nitrogen adsorption-desorption isotherms using the Brunauer-Emmett-Teller (BET) equation at a relative pressure range of 0.03-0.25.…”

“…It was related to a completely different polymers conformation at pH 3. PAA occurs in a coiled form and can be adsorbed both on the surface and in the pores of adsorbents, whereas developed PEI chains are mainly adsorbed only on the outer surface of activated carbons [17]. Moreover, the surface charge of the adsorbents at pH 3 was positive, which resulted in attraction between the anionic polymeric coils and the activated carbon particles.…”

Surface Treatment of Biochar: Methods, Surface Analysis and Potential Applications. A Comprehensive Review

“…Another type of biochar/polymer composites can be prepared by mixing biochar with PEI, using methanol or ethanol. [85][86][87][88][89] Electrostatic interaction between the protonated amino groups from the biochar and the carboxylate groups from biochar can take place. Also, strong hydrogen bonds are expected.…”

Surface Treatment of Biochar—Methods, Surface Analysis and Potential Applications: A Comprehensive Review

“…Another type of biochar/polymer composites can be prepared by mixing biochar with PEI, using methanol or ethanol [105][106][107][108][109]. Electrostatic interaction between the protonated amino groups from the biochar and the carboxylate groups from biochar can take place.…”